Containers of various sorts including bottles and cans and jars, etc., are commonly filled with liquid type products in a production line by a rotary type piston filler wherein the containers arrive on a conveyor line and are successively applied onto a turret in underlying relation with a revolving piston type filler. The filler has a piston moving in an upright cylinder, and the piston is reciprocated upwardly and downwardly during revolving of the filler and turret so that the liquid product is drawn into the piston and is subsequently expelled from the piston into the container being filled. The amount of liquid product that is supplied into the container in the filling operation is measured by the magnitude of the piston movement in the cylinder, and the size of the cylinder.
The vertical reciprocation of the pistons is conventionally controlled by a cam follower or roller moving between circumferential or belt type cam bars having somewhat of an undulating shape in a direction along the turret axis, while at all locations being equidistance from the turret axis to permit the cam follower or roller to be continuously confined between the two guide rails.
In the past, it has been conventional to adjust the quantity of liquid drawn into the pistons by tipping or adjusting the magnitude of the undulation in the cam rails surrounding the rotating filling machine. This technique simultaneously adjusts the quantity of liquid filled into all the cylinders, and all the containers being filled. However, because of the accuracies demanded by governmental authorities, and in order to give the customers of the liquid product their full measure, this type of control of the measuring of the liquid product has proved unsatisfactory. In order to make sure that an adequate amount of liquid product is supplied into the container, the adjustment tends to overfill certain of the containers if there is any minute difference between the quantities drawn and expelled from the piston fillers.
In the prior art apparatus there is no provision made for compensating between variations in sizes as between adjacent cylinders on the turret. A variation in cylinder diameter in the range of 0.003 to 0.004 inches can make a significant difference in the quantity of liquid product being measured. Likewise, the seals between the pistons and the cylinders need changing from time to time, and variations in the seals as between new seals and old seals and possibly in redesigned seals to produce a sealing effect on various types of liquids can have a significant effect upon the internal volume of the cylinder into which the liquid product is drawn. The prior art filling machines have made no provision at all for making fine adjustments to compensate for the sizes of the cylinders and the volume of the chambers defined thereby, and likewise, there is no possibility in the prior art apparatus for adjusting for any possible leakage that might conceivably occur on a temporary basis.